# A balanced lever has two weights on it, the first with mass #3 kg # and the second with mass #4 kg#. If the first weight is # 8 m# from the fulcrum, how far is the second weight from the fulcrum?

##### 1 Answer

6 m away from the fulcrum, opposite from the first weight.

#### Explanation:

For the lever to be "balanced", there must be *no net torque* on the system, or

or

Assuming the fulcrum is at the center of mass of the lever (or the lever is *massless*), the torques created by each of the weights must be **equal and opposite**:

**Torque** is the force perpendicular to a point of rotation multiplied by the distance from that pivot point. Assuming the lever to be *horizontal*, the torque equation becomes:

Solving for

Applying the given information, we get:

The fact that *negative* value tells us that it is on the opposite side of the fulcrum from the first weight.

**The second weight must be positioned 6 m away from the fulcrum on the other side of the fulcrum.**